Variable pitch propeller



Feb. 25, 1947. P, M MAN 2,416,541

u VARIABLE PITCH PROPELLER Filed Aug. 30, 1943 2 Sheets-Sheet l tlnnn n A WE 4 'Z/ 30 l 'I mw n l 31 24 15a, Q/ n 35 j A 17 PETE'QM/CHAEL OLMA/v, 1 NVE NToR.

ATTORN E Y.

Feb. 25,1947. ,Q M, OLMAN 2,416,541

VARIABLE PITGH PROPELLER Filed Aug. 50, 1943 2 sheets-sheet 2 PETE@ 1111/649454 OLMA/v,

l N V E N TO R ATTORN EY. l

Patented Feb. 25, 1947 UNITED STATES PATENT OFFICE VARIABLE PITCH PROPELLER n i Peter Michael mman, Los Angeles,` Calif. y Application August so, 194e, serial N6.,5ofo,499

This invention relates. o propellersand is particularly adapted for use'in the construction of propellers for aircraft, although features of the invention may be employed in the construction of propellers for other uses.

A motor. driving a propeller should preferably rotate uniformly atthe speed for which it is designed, as ordinarily that is the speed at which cally to the speed of rotation, so that if the mo tor tends to rotate at an abnormally high rate of speed the pitch of the blades will automatically be increased, and vice versa. y Another object ofthe invention lis to provide a construction for the propeller that will enable the pitch of the blades to adapt itself automatically to the density of the airvatdthe flying level of the aircraft, so that although the vair at a higher elevation is more 4rareiledthe -pitch of the propeller blades will automatically be in-` creased to meet this condition. `This of course operates to keep the motor turning at a uniform speed.

A further .object of the invention vis to provide a construction in which centrifugal weights areV housed in the shanks of the propeller blades, for automatically varying the pitch of the blades, in

order to accomplish the general purposes of the invention.

It is also an object of lmy invention to provide an organization of parts that is capable of being set to adapt thepropellerfor running at different selected speeds. L y. Additional objects ofthe invention will appear from the following specification and the accompanying drawing, in which: I

Fig. 1 is a plan view illustrating my invention as applied Ato a two-bladed propeller; in this view the outer ends of the bladesv are brokenaway, and

the propeller shank and propeller. hub are also broken away and shown in section. i

Fig. 2 is an enlarged vertical section taken in4 the plane of the line 2-2 in Fig. 1. Fig. 3 is a View similar to Fig. 1, but showing' only the innerendsv of Athe blade shanks; this The energy abr.

f 12 Claims. (014170-162) v I 2 view is alsoupon a larger scale and shows in section and more in detail the parts that enable the. propeller to beset to run at certain .predetermined speeds.

Fig. 4 is a section taken` in the plane of the, line 4-4 in Fig. 3 further illustrating the preferred construction for the controlling parts asso-y ciatedwith the'propeller hub.- f In-practicing the invention, vfprovidea pro' peller shaft- ,I,. at or n,ear..thexend of. which I, mount the blades .2. In'the' present instance; there are two radially-extending blades located diametrically opposite to each other, but of course three or more blades may be employed if. desired. Each blade is formed with a tubular. shank 3 that carries the' blade body, andY each blade body is formedwith 4pitch in the usual' manner. The inner` ends ofthe Shanks 3 are mountedfor rotation on their longitudinal axes, which are preferably .located Yperpendicular to the axis of the propeller shaft. Y

The baseof each tubular shank is swiveled on a neck of a stub-pintle. I-a that projects later#A ally from the propeller shaftl around which is located an inner bearing 4, preferably formed, as an anti-friction bearing such as a roller bearing, or a duplex ball bearing such as illustrated. Eachj shank is"f rmed .at its-inner end` with an annular. shoulder 5over which'is secured a retainer, prefera't'ily consisting f a collar B..With a roller bear. ing`1 ora plurality of s'uch bearings to take the. outwardqthrustfo'f .thefblades These retainerf collars 6 may, ,if desired, be threaded onto'circular bosss'located at the `propeller hub in a,c.

cordance with com-mon practice, or they maybe.

secured at their inboard edges to the hub byY means of a plurality of 4bolts or machine screws such as the screws 8 illustrated in Fig. 2. v Each propeller shank`3 houses a centrifugal governorI means that preferably includes va cen'- trifugal weight or block 9, thatresembles a piston` head in form, and Vwhich is capable of moving in or out in the chambera of shank 3 depending "upon theaction of centrifugal force; The

heads 9 are-prevented from rotationabout their own axes duringr their axialmovement in the shank chamber Bal and'to this" end', Iprefervto provide an arbor I0,.coaxia1 with each' shank, that extends out througha'central guide opening Il in the head 9. These arbors are constructed so that` the heads 9 are nonrotatable thereon', andfor this purpose a feathered or splined conf nection may be employed, or the arbors may be of angular 'formin cross-section, for example,

octagonal, hexagonal or of square form as shown in the drawing for the purpose of illustration.

i The outer surface of each centrifugal head has a substantially helical screw thread connection I2 with the inner wall of the shank 3, and by reason of this connection, the outward or inward movement of each head 9 will cause an adjustn ing rotation of the shank 3 which will vary the pitch of its. propeller; blade. Y

` As the. weights 9 travel outwardly., they meet-v with increasing but yielding resistance, preferably occasioned by coil springs I3 coaxial on the.x arbors I9, with the inner end of each spring thrusting against the headV `9. In thel presentv instance, the outer end of each spring, is attached.. to the outer portion of each arbor, preferably by forming a radical spur on its outerl end that is `in the sleeve. The rear ends of these draw bars I outer ends of the arbors I0, they are formed respectively with round tail ends or necks 36 i (-.see- Fig. V2).A that, can slide androtateein a correspendingY guide bore 21 in the. outer portion of the shank 3, and if desired, a ball bearing 28 may be `provided in the counterbore 29 shown at this point.

Of course, the neck 26 slides freely through the inner ring 28a of the bearing 28.

received in a drill hole or socket I4 in the arbor.

The strength and position of the springs I3 are correlated'with the. heads 9 so that the blades will assume the proper pitch forl normal engine speeds. If the motor'tends to rotate at' a higher speed than normal, the increased centrifugal forcev available will force. the heads' 9' outwardly. against the action of, the springs I3., ,beyond their normal position. This outward movement of heads 9 Vwill rotate the shanks 3, thereby increasing the propeller bite. This in turn will slow down the engine to its' normal speed. Even slight variations in motor' speed will start this, cycle of operationsr thus givingl continuous instantaneous adjustment'. The springs are also proportioned so that when the motor stops, the heads 9 will be forced inwardly to their.V extreme basel position,

in which position the. bladeswill be completely feathered'.

The inner ends of the arhorsV I9 are preferablyv mounted so that they can be adjusted. in or out to. different extents to change the amountl of normal compression in the springs. I3, thereby enablingl the springs to be set to adapt them for different engine. speeds. Counterbores 29 are provided to accommodate the outer ends of the springs whenA the arbors are moved outwardly.. This adapts. the propeller for use with different makes or types of' engines, and also aiords an adjustment for adapting the, propellerl for nor.- mal flying, at any desired' elevation. The adjust.'- ment is preferably accomplished by' means of' a cam l5 keyedv as at |52;4 against rotation., and mounted to slide in the chamber I6 thatgis; formed at the forward endl of the shaft I`. This cam may have thev general form. of' a plug or long piston (see. Fig. 3) and is' preferablyV provided with undercut cam slots f1'. Each of these slots has a gateway or mouth I which iswide enoughy in a radial" direction to. permitY inclined T heads' I9 carried by the arhorsY to` slip intoy them-when the cam is slipped into the forward end of` the chamber I6 when assembling these parts: The cam slotsl preferably diverge or incline outwardly tow-ardI the periphery of' they cam.

` The cam I5' can be shifted at will` to any desired' position by shifting the4 sleeve- 20T forward or backii'n rthe shaftn I, because the. forward head 2I of the sleeve 23 isv securedto: the: cam.. means of a shouldered pintle 2.2. andits nut.,

lY The sleeve 2U has diametrical oppositely located clearance slots 2:3; through which. the stnb-pntles I -a1 andA their enlarged. bosses, 24 tsee; Fig.A 2); project.. The. sleeve' is slid. into; place .over the front end of Vtheshaft. and, its position is, con-1 trolled. by two o-pposed links; or draw bars .25, theV ends ofV which terminate respectively in: arcuate yokes a that lie in a circumferential glQOVC 25 The, centrifugalA heads 9 are preferablypro- "vided with vents 9a which give communication shanks 3 may be formed withgear. teeth 39 that mesh with idler pinions 3| rotatably mounted i on studs 32, and meshing onl their inneredges.

with a large lgear 33 between them, mounted on a center stud 34'. These studs may allbe mounted on a flat seat or face 35 on the sid'e of the shaft` I`..

If desired7 the cam I5` maybe set with respectv to the pitch. phase of' theY blades, so. that movement of the cam beyond a certain point will.

reverse the pitch of each blade to. give abraking effect tending to reduce the speed of the aircraft very promptly.,

The embodiment of the" invention describedv above is of course only one of the many forms.

` this invention may take, and it is to bev understood that I do not mean to be restricted to the, details shown, but intend that my invention shall be accorded the fullscope o f the appended claims.

I claim.; v

L. A propeller having automatic, pitch control including: a rotatable, propeller hub; blades with shanks mounted for. rotation om their o wn axes.

and extending in a. radial direction from thehub.;

'. rotation of each blade on the axisI of its shank. to. alter its, pitch; means tor. yieldne'flyv resisting the outward movement of the weghtsunder the.

action of the centrifugal force; and. means .forVK drawing said. arbors. inwardA to increase. the resistance.. of said;v yieldingly resistant means..

2.. A propeller including a. propeller shaft;

plurality of, blades. each having. ashankmeunted on the propeller shaft for rotation on. the. axis. of the.. shank; a. centrifugally controlled weight in each shank operating to. move. out under the. Vaction of the centrifugal. force; means. actuated by the in andout movement of. the weight to. eect.

a rotational adjustment ofthe shankto alter the pitch of each blade; resistance means for yieldingly resisting the outward movement of each weight; and means including a cam mounted in the propeller shaft for adjusting the resisting force of said resistance means.

3. A propeller including a propeller shaft; a plurality of blades, each having a shank mounted on the propeller shaft for rotation on the axis of the shank; a centrifugally controlled Weight in each shank operating to move out under the action of the centrifugal force; means actuated by the in and out movement of the weight to effect a rotational adjustment of the shank to alter the pitch of each blade; an arbor in each shank extending outward past the Weight; a coil spring thrusting againstv each weight and connected to the arbor; and a cam guided to move longitudinally of the propeller shaft land connected with the inner ends of the arborsfor adjusting the same in or out in the Shanks to alter the re sisting force of the springs and thereby adapt the same for different speeds of rotation of the pro peller shaft. Y

4. A propeller according to claim 3 in which the cam is formed with cam slots operatively connected with the inner ends of the arbors for adjusting the same in or out.

5. A propeller according to claim 3 in which the cam is formed with cam slots operatively connected to the inner ends of the arbors for adjusting the same in and out; and including a sleeve guided to shift longitudinally on the propeller shaft and connected to the cam for actuating the same.

6. A propeller according to claim 3 in which a sleeve is mounted to slide longitudinally on the shaft, attached at its outer end to the cam, and having longitudinal slots corresponding to the several blades, the inner ends of the shanks being attached to the shaft through said longitudinal slots.

7. A propeller having automatic pitch control including: a rotatable propeller hub; blades with shanksmounted for rotation on their own aXes and extending in a radial direction fromthe hub; centrifugally controlled means including a weight guided to travel in and out along a radial line from the axis of the hub; an arbor corresponding to each blade extending outwardly from the propeller hub on the axis of the shank, passing through the weight for that blade; each arbor and its corresponding weight having correlated form enabling the arbor to prevent rotation of the Weights on the axes of the Shanks; each Weight and each blade having a thread connection between the same operating to effect an adjusting rotation of each blade on the yaxis of its shank to alter its pitch; a coil spring associated with each arbor and having its outer end connected to its corresponding arbor and its inner end pressing against the outer side of its corre spending weight to thereby yieldingly resist the outward travel of the Weight; and means mounted in the hub for drawing the arbors inward to increase the resistance of said springs to the outward travel of the governor weights, thereby adapting the blades for a relatively high speed of rotation of the propeller shaft.

8. A propeller including a propeller shaft; a plurality of blades, each having a shank mounted on the propeller shaft for rotation on the axis of the shank; a centrifugally controlled weight in each shank operating to move out under the action of the centrifugal force; means actuated by the in and out movement of the Weight to alter the pitch of each'blade;'means for resisting i effect a rotational adjustment of the shank to the outward movement of each Weight; means i'ncluding a cam mounted in the propeller shaft for adjusting said resisting force; a sleeve lmounted to slide longitudinally on said shaft and attached to said cam to move the same; and means for sliding said sleeve to operate said cam.

9. A propeller including a propeller shaft; a plurality of blades, each having a shank mounted on the propeller shaft for rotation on the axis of the shank.; a centrifugally controlled .Weight in each shank operating. to move out underfthe action of the centrifugal force; means actuated by the in and outY movement of the weight to effect a rotational adjustment of the shank to"r alter the pitch of each blade; an arbor in each yielding means and thereby adapt the same forv different speeds of rotation of shaft.

10. A propeller according to claim v9 in which the cam is formed with cam slots operatively connected With the inner ends of the arbors for adjusting the same in or out.

I 11. A propeller according to claim 9 in which the cam is formed with cam slots operatively connected to the inner ends of the arbors for adjusting the same in and out; and including a sleeve guided to shift longitudinally on the propeller shaft and connected to the cam for actuating the same.

l2. A propeller according to claim 9 in. which a sleeve is mounted to slide longitudinally on the shaft, attached at its outer end to the cam. and having longitudinal slots corresponding to the several blades, the inner yends of the'shanks being' attached to the shaft through said longitudinal slots.

the propeller PETER MICHAEL OLMAN.v y REFERENCES CITED The following references are of record in the le of this patent: f

UNITED STATES PATENTS Number Name Date 1,449,685 Luther et al Mar. 27, 1923 4 2,237,030 Gathmann Apr. 1, 1941 2,275,361 Godfrey Mar. 3, 1942 1,648,837 Anderson Nov. 8, 1927 1,979,616 Haidle Nov. 6, 1934 2,307,102 Blanchard Jan. 5, 1943 1,328,241 Weaver Jan. 13, 1920 2,054,947 Riddle Sept. 22, 1936 2,125,222 Evans July'26, 1938 1,833,403 Newton Nov. 24, 1931 1,837,568 Moody Dec. 22, 1931 2,177,535, Platt Oct. 24, 1939 2,234,521 Insua May 26, 1942 1,405,643 Weaver Feb. 7, 1922 2,013,647 Bace Sept. 10, 1935 2,257,126 Rindfleisch Sept. 30, 1941 FOREIGN PATENTS Number Country Date 629,361 German Apr. 29, 1936 630,650 France Dec. 6, 1927 r215,941 British May 22, 1924 14,635 British 1910 

